It has heretofore been known that in a system of processing signals from a plurality of detection elements, one ends of the plural detection element are made common for a reduction in the number of terminals and due to structural constraints (refer to, for example, Patent Literature 1).
It has also been known that in a circuit which processes signals from sensors in which one ends of a plurality of detection elements are made common, a chopper operation adapted to perform signal processing by switching the orientation of each detection element is performed to cancel an offset.
Further, there has been proposed an infrared sensor module equipped with an infrared sensor, an IC element which performs signal processing on an output signal of the infrared sensor, and a package in which the infrared sensor and the IC element are stored. Moreover, it is general that in a semiconductor device such as an IC, an ESD protection circuit is provided on a chip to prevent the device from destruction due to electrostatic discharge (ESD: Electro-Static Discharge).
A sensor device equipped with a sensor element and an IC element signal-processing an output voltage of the sensor element often amplifies the output voltage to perform its signal processing because the amplitude of the output voltage of the sensor element is small and the output impedance of the sensor element is high. For example, since in the above-described infrared sensor module, the amplitude of the output voltage of the infrared sensor as the sensor element is small, and the output impedance of the infrared sensor is high, an amplifier circuit which amplifies the output voltage of the infrared sensor, an A/D conversion circuit which analog-to-digital converts the analog output voltage of this amplifier circuit, etc. are considered to be provided in the IC element.
For example, the sensor device described in Patent Literature 2 relates to a sensor device in which an ESD protection circuit is provided in each of an infrared sensor as a sensor element and an IC element. This is one provided with offset canceling unit which, in order to avoid the occurrence of an offset voltage caused by a leak current flowing through each ESD protection circuit and a reduction in S/N ratio, cancels an offset voltage determined by a leak current flowing through a sensor unit due to a first ESD protection circuit and a second ESD protection circuit and the impedance of the sensor unit.
Further, there has been illustrated in Patent Literature 3, a configuration which is provided with a sensor element, a signal processing device that processes an output current of the sensor element, and a correction arithmetic unit that performs a temperature correction, and in which the output current from the sensor element is converted into a voltage by a current-voltage converter.
Moreover, there has been illustrated in Patent Literature 4, a configuration which is provided with a sensor unit, a switch, and a full differential amplifier and performs signal processing on an output voltage from the sensor unit. In this Patent Literature 4, the output voltage from the sensor unit is chopper-modulated by the switch to perform its signal processing.